U.S. patent application number 13/699755 was filed with the patent office on 2013-04-04 for microspheres and photoprotective personal care composition comprising same.
The applicant listed for this patent is Sudipta Ghosh Dastidar, Bharath Palanisamy. Invention is credited to Sudipta Ghosh Dastidar, Bharath Palanisamy.
Application Number | 20130084318 13/699755 |
Document ID | / |
Family ID | 44317939 |
Filed Date | 2013-04-04 |
United States Patent
Application |
20130084318 |
Kind Code |
A1 |
Ghosh Dastidar; Sudipta ; et
al. |
April 4, 2013 |
MICROSPHERES AND PHOTOPROTECTIVE PERSONAL CARE COMPOSITION
COMPRISING SAME
Abstract
The invention relates to photoprotective cosmetic compositions
comprising microspheres and a process to prepare them. In
particular, the invention is especially effective in protecting the
skin against visible solar radiation while ensuring a highly
acceptable even skin tone and appearance. The present inventors
have developed a microsphere with hollow interior and shell of a
material having a specific optical property and specific thickness
and coated with another material having a different specific
optical property, a combination of which gives the microsphere
surprising benefits both in terms of protection from the harmful
sun rays while giving a pleasing skin appearance when these
microspheres are incorporated in topical compositions.
Inventors: |
Ghosh Dastidar; Sudipta;
(Bangalore, IN) ; Palanisamy; Bharath; (Bangalore,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ghosh Dastidar; Sudipta
Palanisamy; Bharath |
Bangalore
Bangalore |
|
IN
IN |
|
|
Family ID: |
44317939 |
Appl. No.: |
13/699755 |
Filed: |
May 19, 2011 |
PCT Filed: |
May 19, 2011 |
PCT NO: |
PCT/EP2011/058098 |
371 Date: |
November 26, 2012 |
Current U.S.
Class: |
424/401 ; 424/59;
427/222 |
Current CPC
Class: |
C01P 2004/34 20130101;
C09C 3/12 20130101; A61K 8/8152 20130101; C09C 1/3684 20130101;
A61K 2800/412 20130101; C01P 2004/86 20130101; C01G 23/08 20130101;
C09C 1/043 20130101; A61K 2800/621 20130101; C01P 2002/84 20130101;
C09C 1/3607 20130101; B05D 5/00 20130101; A61K 8/0279 20130101;
C09C 3/063 20130101; C01G 19/02 20130101; C09C 1/3669 20130101;
A61Q 17/04 20130101; B82Y 30/00 20130101; A61K 8/27 20130101; C01P
2004/61 20130101; B01J 13/22 20130101; C09C 1/3661 20130101; C09C
3/08 20130101; C01P 2006/60 20130101; C01G 23/047 20130101; C01P
2004/64 20130101; C01P 2004/03 20130101; C01G 9/02 20130101; A61K
8/29 20130101 |
Class at
Publication: |
424/401 ; 424/59;
427/222 |
International
Class: |
A61K 8/02 20060101
A61K008/02; B05D 5/00 20060101 B05D005/00; A61K 8/81 20060101
A61K008/81 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2010 |
IN |
1715/MUM/2010 |
Aug 24, 2010 |
EP |
10173855.7 |
Claims
1. A photoprotective personal care composition comprising (a) a
microsphere of 100 to 600 nm mean diameter comprising a. a coated
shell; and b. a hollow core comprising air; said shell of 20 to 100
nm thickness comprising a metal oxide having a refractive index in
the range of 1.8 to 3,0; said shell coated with a coating material
having a refractive index in the range of 1.3 to 1.6; said coating
material of thickness in the range of 10 to 30 nm; and (b) a
cosmetically acceptable base.
2. A composition as claimed in claim 1 wherein said metal oxide is
titanium dioxide or zinc oxide.
3. A compost on as claimed in claim 1 wherein said coating material
is transparent to light in the wavelength range of 200 to 400
nm.
4. A composition as claimed in claim 1 wherein said coating
material is aluminium hydroxide, fatty acid silicone,
polysaccharides or their derivatives.
5. A composition as claimed in claim 1 wherein said coating
material is an organic compound.
6. A composition as claimed in claim 1 wherein said coating
material has a surface energy between
20.times.10.sup.-3-50.times.10.sub.-3J/m.sup.2.
7. A composition as claimed in claim 1 wherein the cosmetically
acceptable base is a cream, lotion, gel or emulsion.
8. A process to prepare microspheres for use in a photoprotective
personal care composition according to any one of the preceding
claims comprising the steps of a. taking hollow polymeric
microspheres in a solvent; b. reacting a precursor of the metal
oxide in the solvent phase to form metal oxide which forms a layer
on the hollow polymeric microspheres thereby forming layered
microspheres; c. separating the layered microspheres from the
solvent; d. calcining the layered microspheres to prepare hollow
metal oxide microspheres. e. preparing a dispersion of the hollow
metal oxide microspheres in a solvent along with the coating
material having a refractive index in the range of 1.3 to 1.6; f.
stirring for a period of 0.5 to 4 hours; g. separating coated
microspheres from the solvent.
Description
TECHNICAL FIELD
[0001] The invention relates to a photoprotective personal care
composition comprising microspheres, and a process to prepare them.
In particular, the invention relates photoprotective personal care
compositions that are effective in protecting the skin against
harmful solar radiation especially from the visible rays while
ensuring a highly acceptable even skin tone and appearance.
BACKGROUND OF THE INVENTION
[0002] Highly pleasing skin appearance is one of the most desired
expectations from cosmetic products from most consumers around the
world. In tropical countries where consumers generally have dark
skin, there is a desire to have lighter skin appearance. In
consumers who live far from the tropical countries e.g. the
Caucasian people who generally have lighter skin, there is a need
among such consumers to have an even tanned tone of their skin. Any
exposure of the skin to sunlight, in such consumers often leads to
blochy skin, referred to as freckles and in some cases they
experience hyperpigmentation in localized areas of the skin. Most
consumers experience blemishes on their skin after exposure to sun,
on healing of wounds or after drying up of acne. In all of the
above cases, consumers rely on cosmetic solutions to their skin
appearance problems.
[0003] Smooth, soft and glowing skin with even skin tone and colour
is thus desired by all consumers who use cosmetic compositions for
their skin. To provide this benefit, manufacturers from around the
world have tried many approaches. One very commonly used approach
is to include sunscreens or sunblocks in such cosmetic products.
Sunscreens or sunblocks may be organic compounds or inorganic
compounds. Sunscreens are generally organic compounds that work by
absorbing ultra-violet (uv) radiation from the sun at specified
wavelength range thus not permitting the uv radiation from reaching
the skin surface. UV radiation is believed to be the cause of skin
coloration or tanning and if such tanning is uneven, it is disliked
by the consumer. Sunblocks are generally inorganic compounds that
act as physical barrier against a wide range of radiation from the
sun (both uv and visible light). There are some disadvantages in
both these approaches. Organic sunscreens are generally effective
only against specific wavelength ranges i.e. they are not broad
spectrum and therefore more than one sunscreens are often to be
used. There are also questions about the stability of these
sunscreens on exposure to the sun. Inorganic sunblocks, while being
broad spectrum, often are white in colour and leave a pale whitish
appearance on the skin which is unnatural and not liked by
consumers.
[0004] Another approach used by cosmetic researchers is to provide
instant appearance benefit by incorporating tailor made materials
or particles in cosmetics. Such materials or particles optically
interact with the light incident on the skin and reflect light in
such a wavelength range that makes the skin appear to have a
desired colour, tone and evenness.
[0005] One or a combination of the above approaches is used in many
cosmetic products. In order to provide all or most of the benefits,
many different ingredients, each having a specific benefit and
working through a specific mechanism need to be incorporated in the
skin compositions. Some of these ingredients may interact with each
other or may be unstable in the cosmetic base.
[0006] In order to provide a solution to the above problem the
present inventors have been working for many years on developing
tailor made materials that work through multiple routes to provide
most of the skin cosmetic benefits in a single material. In the
present invention the inventors have developed microspheres that
combine the unique benefits of photoprotective materials and
materials that provide instant optical benefits to deliver a
product having benefits not achieved before.
[0007] WO 02/074431 (Max Planck) relates to a preparation of
monodisperse hollow titania spheres with defined diameter, wall
thickness and crystal phase. The hollow spheres have been produced
by the layered deposition of water-soluble titania precursor onto
submicron sized template particles, e.g. polystyrene particles,
followed by calcination at elevated temperatures.
[0008] US 2009/0155371 (Sojka) discloses topical compositions
containing solid particles that are stabilized via entrapment by
microspheres, each microshpere containing a collapsed polymeric
shell that has entrapped therein one or more solid particles.
[0009] U.S. Pat. No. 6,534,044 (Showa Denko K K) discloses a
cosmetic material comprising silica coated metal oxide particles
further surface coated with a hydrophobizing agent .
[0010] The present inventors have developed a microsphere with a
hollow interior and a shell of a material having a specific optical
property and specific thickness and coated with another material
having a different specific optical property, a combination of
which gives the microsphere surprising benefits both in terms of
protection from the harmful sun rays while giving a pleasing skin
appearance when these microspheres are incorporated in topical
compositions. This microsphere has also been prepared by a novel
process that gives the material these unique properties, through a
simple and easy to scale up process.
[0011] It is thus an object of the present invention to provide for
a material that when incorporated in a photoprotective personal
care composition for giving the combined benefits of
photoprotection over a wide range of wavelengths while at the same
time giving the skin a pleasing even appearance.
[0012] It is another object of the present invention to provide for
a process to prepare a material that can be incorporated in
personal care compositions for both photoprotection over a wide
range of wavelengths and pleasing even appearance to the skin where
the cosmetic is applied.
[0013] It is yet another object of the present invention to provide
for a material which can be incorporated in personal care
compositions which give the combined benefits of wide spectrum
photoprotection and benefits of instant lightening of the skin for
dark skinned consumers without the skin appearing unnaturally white
and pale.
SUMMARY OF THE INVENTION
[0014] According to one aspect of the present invention there is
provided a photoprotective personal care composition comprising
[0015] (a) a microsphere of 100 to 600 nm mean diameter comprising
[0016] (i) a coated shell; and [0017] (ii) a hollow core comprising
air; [0018] said shell of 20 to 100 nm thickness comprising a metal
oxide having a refractive index in the range of 1.8 to 3.0; said
shell coated with a coating material having a refractive index in
the range of 1.3 to 1.6.and [0019] (b) a cosmetically acceptable
base.
[0020] According to another aspect of the present invention there
is provided a process to prepare microspheres for inclusion in
photoprotective personal care compositions comprising the steps of
[0021] (i) taking hollow polymeric microspheres in a solvent;
[0022] (ii) reacting a precursor of the metal oxide in the solvent
phase to form metal oxide which forms a layer on the hollow
polymeric microspheres thereby forming layered microspheres; [0023]
(iii) separating the layered microspheres from the solvent; [0024]
(iv) calcining the layered microspheres to prepare hollow metal
oxide microspheres. [0025] (v) preparing a dispersion of the hollow
metal oxide microspheres in a suitable solvent along with a desired
coating material; [0026] (vi) stirring for a period of 0.5 to 4
hours; [0027] (vii) separating coated microspheres from the
solvent.
BRIEF DESCRIPTION OF THE FIGURES
[0028] The invention is described in more detail hereinbelow with
reference to the figures in which:
[0029] FIG. 1(a) shows a SEM image of Sunsphere.sup.TM hollow
polymeric microspheres used for preparing the hollow microspheres
of the invention;
[0030] FIG. 1(b) shows a SEM image of hollow microspheres of the
invention prepared as per example 1;
[0031] FIG. 2(a) shows transmittance spectra in the visible region
of a composition as per invention (example 2) as compared to a
conventional composition (example 3);
[0032] FIG. 2(b) shows transmittance spectra in the UV region of a
composition as per invention (example 2) as compared to a
conventional composition (example 3); and
[0033] FIG. 3 shows absorbance spectra of a model dye solution
which demonstrate the superiority of coated microspheres for
incorporation in the composition of the invention as compared to
uncoated microspheres.
DETAILED DESCRIPTION OF THE INVENTION
[0034] These and other aspects, features and advantages will become
apparent to those of ordinary skill in the art from a reading of
the following detailed description and the appended claims. For the
avoidance of doubt, any feature of one aspect of the present
invention may be utilised in any other aspect of the invention. The
word "comprising" is intended to mean "including" but not
necessarily "consisting of" or "composed of." In other words, the
listed steps or options need not be exhaustive. It is noted that
the examples given in the description below are intended to clarify
the invention and are not intended to limit the invention to those
examples per se. Similarly, all percentages are weight/weight
percentages unless otherwise indicated. Except in the operating and
comparative examples, or where otherwise explicitly indicated, all
numbers in this description and claims indicating amounts of
material or conditions of reaction, physical properties of
materials and/or use are to be understood as modified by the word
"about". Numerical ranges expressed in the format "from x to y" are
understood to include x and y. When for a specific feature,
multiple preferred ranges are described in the format "from x to
y", it is understood that all ranges combining the different
endpoints are also contemplated.
[0035] By "photoprotective personal care composition" as used
herein, is meant to include a composition for topical application
to sun-exposed areas of the skin and/or hair of mammals, especially
humans. Such a composition may be generally classified as leave-on
or rinse off, and includes any product applied to a human body for
also improving appearance, cleansing, odor control or general
aesthetics. The composition of the present invention can be in the
form of a liquid, lotion, cream, foam, scrub, gel, soap bar or
toner, or applied with an implement or via a face mask, pad or
patch. Non-limiting examples of photoprotective sunscreen
compositions include leave-on skin lotions and creams, shampoos,
conditioners, shower gels, toilet bars, antiperspirants,
deodorants, lipsticks, foundations, mascara, sunless tanners and
sunscreen lotions. "Skin" as used herein is meant to include skin
on the face and body (e.g. neck, chest, back, arms, underarms,
hands, legs, buttocks and scalp), especially to the sun exposed
parts thereof. The composition of the invention is also of
relevance to applications on any other keratinous substrate of the
human body other than skin, e.g. hair, where products may be
formulated with specific aim of providing photoprotection.
[0036] The invention relates to a microsphere, method of preparing
the same and cosmetic compositions comprising them. The
microspheres of the invention are of the core shell type. The core
is hollow, i.e it merely comprises air. By the term hollow is meant
that the core of the microsphere is substantially free of any solid
or liquid material. Preferably the core comprises more than 90
volume percent air, more preferably more than 95 volume percent
air. The shell has a mean diameter of 100 to 600 nm, more
preferably 300 to 400 nm, further more preferably 300 to 350 nm. By
mean diameter is meant the number average mean diameter of the
particles. In this specification, the particle size distribution of
commercial particles were determined using Malvern particle size
analyzer. The diameter of the hollow microspheres of the invention
were determined using dynamic light scattering instrument
(purchased from Brookhaven) which was coupled with a Lexel 95 laser
(wavelength of 488 nm). The selective mean particle diameter in
these preferred ranges provides for the optimum visible light
scattering to ensure the desired photoprotection while maintaining
the desired skin appearance. The shell has a thickness of 20 to 100
nm, more preferably 20 to 60 nm, further more preferably 20 to 30
nm. In these selective ranges of shell thickness the advantages are
to ensure the desired UV ray scattering to meet the objectives of
the invention viz. optimum photoprotection and skin appearance. The
shell thickness of the hollow microspheres was determined from
their SEM images. Image analysis using Image Pro Plus software was
used to evaluate the shell thickness from the SEM images. The shell
is made of a metal oxide having a refractive index of 1.8 to 3.0,
more preferably 1.9 to 2.7. Metal oxides having a refractive index
in the range of 1.8 to 3.0 are necessary in order to provide
enhanced efficacy of light scattering. The metal oxide from which
the shell is made is preferably titanium dioxide, zinc oxide, tin
oxide or cerium oxide more preferably titanium dioxide or zinc
oxide. The refractive indices for the various materials mentioned
in this specification are those reported in well known databases
like `The Handbook of Chemistry and Physics`, Publisher, CRC Press
Boca Raton, Fla.
[0037] The shell is coated with a material having a refractive
index in the range of 1.3 to 1.6, more preferably 1.4 to 1.6.
Coating with a material having this selective refractive index is
especially useful to reduce photocatalytic activity of these
microsphere particles. High photocatalytic activity of these
particles is undesirable for skin applications. Further, this
selective property enhances dispersion and ensures spreading of the
cosmetic composition on the skin applied on. The coating with a
material having a refractive index in the range of 1.3 to 1.6 is
preferably of a thickness in the range of 10 to 30 nm. It is
preferred that the material coated on the shell is transparent to
light in the wavelength range of 200 to 400 nm. By the term
"transparent to light in the wavelength range of 200 to 400 nm" is
meant that the % transmittance as a function of wavelength from 290
to 400 nm is more than 50%.
[0038] Example of materials which are useful for coating the shell
are silica, aluminium hydroxide, fatty acid, silicone,
polysaccharides and their derivatives. Suitable polysaccharides
include, starch, cellulose, cellulose acetate and cationically
modified starch. Preferred coating materials are fatty acids,
silicones or celluloses. Of the coating materials those which are
organic compounds are more preferred. Another useful property for
selecting suitable coating materials is that they have surface
energy between 20.times.10.sup.-3 and 50.times.10.sup.-3 J/m.sup.2,
more preferably between 30.times.10.sup.-3 and 40.times.10.sup.-3
J/m.sup.2. Selecting coating materials having the above properties
provide for enhanced compatibility of the microspheres in cosmetic
compositions while ensuring even spreading of the compositions on
the topical surface where it is applied.
[0039] Surface energy is the energy required to increase the
surface area of a substance by unit area. Surface energy values
mentioned in this specification are the values for materials as is
mentioned in standard databases found in The Handbook of Chemistry
and Physics' Publisher, CRC Press Boca Raton, Fla., Edited by:
Brandrup, J.; Immergut, Edmund H.; Grulke, Eric A.; Abe, Akihiro;
Bloch, Daniel R., 2005, John Wiley & Sons.
[0040] Without wishing to be bound by theory it is believed that
the combination of the hollow core, i.e. a core comprising air, and
a shell having a refractive index between 2.0 and 3.0 which is
coated with a coating material having a refractive index between
1.3 and 1.6 provides for less photocatalytic activity, more
transparency and better dispersion.
[0041] The composition of the invention comprises the microspheres
having the property as disclosed hereinabove together with a
cosmetically acceptable base. The cosmetically acceptable base is
such that the composition is preferably a cream, lotion, gel or
emulsion. The microspheres are preferably present in 0.1 to 10%,
more preferably 1 to 5% by weight of the composition.
[0042] Cosmetic compositions may be prepared using different
cosmetically acceptable emulsifying or non-emulsifying systems and
vehicles. A highly suitable base is a cream. Vanishing creams are
especially preferred. Vanishing cream bases generally comprise 5 to
25% fatty acid and 0.1 to 10% soap. Vanishing cream base gives a
highly appreciated matty feel to the skin. C.sub.12 to C.sub.20
fatty acids are especially preferred in vanishing cream bases,
further more preferred being C.sub.14 to C.sub.18 fatty acids. The
most preferred fatty acid is stearic acid. The fatty acid in the
composition is more preferably present in an amount in the range of
5 to 20% by weight of the composition. Soaps in the vanishing cream
base include alkali metal salt of fatty acids, like sodium or
potassium salts, most preferred being potassium stearate. The soap
in the vanishing cream base is generally present in an amount in
the range of 0.1 to 10%, more preferably 0.1 to 3% by weight of the
composition. Generally the vanishing cream base in cosmetic
compositions is prepared by taking a desired amount of total fatty
matter and mixing with potassium hydroxide in desired amounts. The
soap is usually formed in-situ during the mixing.
[0043] The composition of the invention may additionally comprise a
skin lightening agent. This skin lightening agent is preferably
chosen from a vitamin B3 compound or its derivative, e.g. niacin,
nicotinic acid, niacinamide, or other well known skin lightening
agents, e.g. aloe extract, ammonium lactate, arbutin, azelaic acid,
kojic acid, butyl hydroxy anisole, butyl hydroxy toluene, citrate
esters, 3-diphenylpropane derivatives, 2,5-dihydroxybenzoic acid
and its derivatives, ellagic acid, fennel extract, gluco
pyranosyl-1-ascorbate, gluconic acid, glycolic acid, green tea
extract, hydroquinone, 4-hydroxyanisole and its derivatives,
4-hydroxybenzoic acid derivatives, hydroxycaprylic acid, lemon
extract, linoleic acid, magnesium ascorbyl phosphate, mulberry root
extract, 2,4-resorcinol derivatives, 3,5-resorcinol derivatives,
salicylic acid, vitamins like vitamin B6, vitamin B12, vitamin C,
vitamin A, a dicarboxylic acid, resorcinol derivatives,
hydroxycarboxylic acid like lactic acid and their salts, e.g.
sodium lactate, and mixtures thereof. Vitamin B3 compound or its
derivatives, e.g. niacin, nicotinic acid, niacinamide, are the more
preferred skin lightening agent as per the invention, most
preferred being niacinamide. Niacinamide, when used, is preferably
present in an amount in the range of 0.1 to 10%, more preferably
0.2 to 5% by weight of the composition.
[0044] The photoprotective personal care composition may preferably
additionally comprise one or more uv sunscreens. The uv sunscreens
may be inorganic or organic.
[0045] A wide variety of organic sunscreen agents are suitable for
use in combination with the essential ingredients of this
invention. Suitable UV-A or UV-B sunscreen agents include
2-hydroxy-4-methoxybenzophenone, octyldimethyl-p-aminobenzoic acid,
digalloyltrioleate, 2,2-dihydroxy-4-methoxybenzophenone,
ethyl-4-(bis(hydroxypropyl)) aminobenzoate,
2-ethylhexyl-2-cyano-3,3-diphenylacrylate, 2-ethylhexylsalicylate,
glyceryl-p-aminobenzoate, 3,3,5-trimethylcyclohexylsalicylate,
methylanthranilate, p-dimethyl-aminobenzoic acid or aminobenzoate,
2-ethylhexyl-p-dimethyl-amino-benzoate,
2-phenylbenzimidazole-5-sulfonic acid,
2-(p-dimethylaminophenyl)-5-sulfonic benzoxazoic acid,
2-ethylhexyl-p-methoxycinnamate, butylmethoxydibenzoylmethane,
2-hydroxy-4-methoxybenzophenone, octyldimethyl-p-aminobenzoic acid
and mixtures thereof. Most suitable organic sunscreen are
2-ethylhexyl-p-methoxycinnamate and
butylmethoxydibenzoylmethane.
[0046] A safe and effective amount of sunscreen may be used in the
compositions useful in the subject invention. The composition
preferably comprises from about 0.1% to about 10%, more preferably
from about 0.1% to about 5% of a sunscreen agent.
[0047] Useful inorganic sunblocks are also preferably used in the
present invention. These include, for example, zinc oxide iron
oxide, silica, such as fumed silica, and titanium dioxide.
[0048] Ultrafine titanium dioxide in either of its two forms,
namely water-dispersible titanium dioxide and oil-dispersible
titanium dioxide is especially suitable for the invention.
Water-dispersible titanium dioxide is ultra-fine titanium dioxide,
the particles of which are non-coated or which are coated with a
material to impart a hydrophilic surface property to the particles.
Examples of such materials include aluminium oxide and aluminium
silicate.
[0049] Oil-dispersible titanium dioxide is ultrafine titanium
dioxide, the particles of which exhibits a hydrophobic surface
property, and which, for this purpose, can be coated with metal
soaps such as aluminium stearate, aluminium laurate or zinc
stearate, or with organosilicone compounds.
[0050] By "ultrafine titanium dioxide" is meant particles of
titanium dioxide having an average particle size of less than 100
nm, preferably 70 nm or less, more preferably from 10 to 40 nm and
most preferably from 15 to 25 nm.
[0051] By topical application to the skin of a mixture of both
water-dispersible ultrafine titanium dioxide and oil-dispersible
ultrafine titanium dioxide, synergistically enhanced protection of
the skin against the harmful effects of both UV-A and UV-B rays is
achievable.
[0052] Ultrafine titanium dioxide is the preferred inorganic
sunblock agent as per this invention.
[0053] The total amount of sunblock that is preferably incorporated
in the composition according to the invention is from 0.1 to 5% by
weight of the composition.
[0054] The composition according to the invention may also comprise
other diluents. The diluents act as a dispersant or carrier for
other materials present in the composition, so as to facilitate
their distribution when the composition is applied to the skin. The
composition of the invention preferably comprises water. Water is
preferably present in 35 to 90%, more preferably 50 to 85% by
weight of the composition.
[0055] Diluents other than water can include liquid or solid
emollients, solvents, humectants, thickeners and powders. Examples
of each of these types of vehicle, which can be used singly or as
mixtures of one or more vehicles, are as follows:
[0056] Emollients such as stearyl alcohol, glyceryl
monoricinoleate, mink oil, cetyl alcohol, isopropyl isostearate,
stearic acid, isobutyl palmitate, isocetyl stearate, oleyl alcohol,
isopropyl laurate, hexyl laurate, decyl oleate, octadecan-2-ol,
isocetyl alcohol, eicosanyl alcohol, behenyl alcohol, cetyl
palmitate, silicone oils such as dimethylpolysiloxane, di-n-butyl
sebacate, isopropyl myristate, isopropyl palmitate, isopropyl
stearate, butyl stearate, polyethylene glycol, triethylene glycol,
lanolin, cocoa butter, corn oil, cotton seed oil, olive oil, palm
kernel oil, rape seed oil, safflower seed oil, evening primrose
oil, soybean oil, sunflower seed oil, avocado oil, sesame seed oil,
coconut oil, arachis oil, castor oil, acetylated lanolin alcohols,
petroleum jelly, mineral oil, butyl myristate, isostearic acid,
palmitic acid, isopropyl linoleate, lauryl lactate, myristyl
lactate, decyl oleate, myristyl myristate;
[0057] Solvents such as ethyl alcohol, isopropanol, acetone,
ethylene glycol monoethyl ether, diethylene glycol monobutyl ether,
diethylene glycol monoethyl ether; and
[0058] Powders such as chalk, talc, fullers earth, kaolin, starch,
gums, colloidal silica sodium polyacrylate, tetra alkyl and/or
trialkyl aryl ammonium smectites, chemically modified magnesium
aluminium silicate, organically modified montmorillonite clay,
hydrated aluminium silicate, fumed silica, carboxyvinyl polymer,
sodium carboxymethyl cellulose, ethylene glycol monostearate.
[0059] The cosmetically acceptable base is usually from 10 to
99.9%, preferably from 50 to 99% by weight of the composition, and
can, in the absence of other cosmetic adjuncts, form the balance of
the composition.
[0060] The compositions of the present invention can comprise a
wide range of other optional components. The CTFA Cosmetic
Ingredient Handbook, Second Edition, 1992, which is incorporated by
reference herein in its entirety, describes a wide variety of
non-limiting cosmetic and pharmaceutical ingredients commonly used
in the skin care industry, which are suitable for use in the
compositions of the present invention. Examples include:
antioxidants, binders, biological additives, buffering agents,
colorants, thickeners, polymers, astringents, fragrance,
humectants, opacifying agents, conditioners, exfoliating agents, pH
adjusters, preservatives, natural extracts, essential oils, skin
sensates, skin soothing agents and skin healing agents.
[0061] The composition is formulated in any known format, more
preferred formats being creams or lotions.
[0062] The composition of the invention may comprise a conventional
deodourant base as the cosmetically acceptable carrier. By a
deodorant is meant a product in the stick, roll-on, or propellant
medium which is used for personal deodorant benefit, e.g.
application in the under-arm or any other area which may or may not
contain anti-perspirant actives.
[0063] Deodorant compositions can generally be in the form of firm
solids, soft solids, gels, creams, and liquids and are dispensed
using applicators appropriate to the physical characteristics of
the composition.
[0064] According to another aspect of the present invention there
is provided a process to prepare microspheres comprising the steps
of taking hollow polymeric microspheres in a solvent; (a) reacting
a precursor of the metal oxide in the solvent phase to form metal
oxide which forms a layer on the hollow polymeric microspheres
thereby forming layered microspheres; (b) separating the layered
microspheres from the solvent; (c) calcining the layered
microspheres to prepare hollow metal oxide microspheres (d)
preparing a dispersion of the hollow metal oxide microspheres in a
suitable solvent along with a desired coating material; (e)
stirring for a period of 0.5 to 4 hours; and (f) separating coated
microspheres from the solvent.
[0065] It is important that the polymeric microspheres for
preparing the microspheres of the invention is hollow. This ensures
that the microspheres of desired size and shape with the hollow
core can be prepared without too many of the microspheres breaking
up during the calcining process. The hollow polymeric microspheres
are preferably made of polystyrene, polyacrylate or polystyrene
co-polyacrylate. The hollow polymeric microspheres preferably have
an inner diameter in the range of 100 to 350 nm and an outer
diameter in the range of 150 to 400. The hollow polymeric
microspheres are first taken in a solvent. Suitable solvents
include ethanol, methanol, propanol or isopropanol. The hollow
polymeric microspheres are taken in the solvent at a temperature
preferably in the range of 60 to 90.degree. C. The hollow polymeric
microspheres dispersed in the solvent is then treated with a
precursor of the metal oxide. Precursors of metal oxides are
generally organometallic in nature, e.g. when titanium dioxide or
zinc oxide are to be prepared, suitable precursors are alkoxides,
sulphates, nitrates, acetates or chlorides more preferably
alkoxides. The hollow polymeric microspheres coated with the
desired metal oxide are then separated from the dispersion and
dried. They are then calcined, preferably at a temperature in the
range of 400 to 800.degree. C. to form hollow metal oxide
microspheres.
[0066] The hollow metal oxide microspheres are then coated with a
coating material having a refractive index in the range of 1.3 to
1.6. Suitable coating materials are cellulose, cellulose acetate,
starch or cellulose ethers e.g. hydroxypropyl cellulose. The
coating process preferably comprises the steps of (i) preparing a
dispersion of the hollow metal oxide microspheres in a suitable
solvent along with the desired coating material; (ii) stirring for
a period of 0.5 to 4 hours; and (iii) and separating the coated
microspheres from the solvent. The separation process is preferably
filtration followed by evaporation of the solvent.
[0067] Preferred solvents during the coating process are acetone or
isopropyl alcohol. To this, the metal oxide particles are dispersed
and stirred until the solvent is completely evaporated.
[0068] The invention is now further described by way of the
following non-limiting examples.
EXAMPLES
Example 1
Preparation of Hollow Microspheres
[0069] Hollow polymeric microspheres (250 mg) made of polystyrene
co-polyacrylate having outer diameter of 350 nm available as
Sunsphere.TM. from Rohm and Haas were taken in a beaker containing
100 ml of ethanol. The hollow polymeric microspheres were suspended
in ethanol through sonication for 30 minutes. To this, 0.72 ml of
water was added and heated to 70.degree. C. on an oil bath and kept
stirred using a magnetic stirrer. Titanium dioxide was coated on
the hollow polymeric microspheres by dropping a precursor viz.
titanium butoxide (2.72 ml) on to the suspension in a dropwise
manner. The reaction was continued for two hours with constant
stirring. The particles so prepared were separated from the
suspension by centrifugation and washed with ethanol and dried. The
dried samples were calcined at 700.degree. C. for five hours in a
muffle furnace.
[0070] The hollow microspheres prepared above were coated using the
following process. 25 mg of cellulose acetate (Fluke) was dissolved
in 100 ml of acetone. To this, 200 mg of the hollow titania
particle prepared above were suspended by sonicating the sample for
30 minutes. After sonication, the sample was stirred in a glass
beaker using a magnetic stirrer until the acetone evaporated
completely. The cellulose acetate coated hollow particle were dried
at 50.degree. C.
[0071] A sample of the coated hollow titania microspheres so
prepared was characterized using
[0072] SEM imaging in comparison to the precursor material i.e. the
hollow polymeric microsphere. The SEM image of the Sunsphere.TM.
sample is shown in FIG. 1a and the coated hollow metal oxide
microspheres of the invention are shown in FIG. 1b.
Examples 2 and 3
Photoprotective Personal Care Compositions of the Invention
(Example 2) Prepared With the Hollow Microspheres of the Invention
in Comparision to a Conventional Composition (Example 3)
[0073] The sample as prepared in example 1 was formulated in a
photoprotective skin care composition (example 2) and compared to a
control composition where the particles of example 1 was replaced
with commercially available micronised titanium dioxide (example
3). The compositions of the samples of examples 2 and 3 are shown
in table 1.
TABLE-US-00001 TABLE 1 Example 2 Example 3 Ingredient (wt %) (wt %)
Hysteric acid 17.00 17.00 Hollow particles of example 1 2.00 --
Micronised titanium dioxide -- 2.00 Glycerine 1.00 1.00 Isopropyl
myristate 0.75 0.75 Potassium hydroxide 0.57 0.57 Cetyl alcohol
0.53 0.53 Silicone oil 0.50 0.50 Methyl paraben + propyl paraben
0.30 0.30 Phenoxy ethanol 0.20 0.20 Disodium EDTA 0.04 0.04 Water
To 100 To 100
[0074] The micronised titanium dioxide used in example 3 was a
commercial sample MT 100Z (Presperse). It is a titanium dioxide
particle that is coated with aluminium hydroxide and aluminium
stearate.
[0075] The samples of example 2 and 3 were compared by measuring
the transmittance spectra in the UV-Vis region using the following
procedure.
[0076] A transpore tape (ex. 3M) was used as a substrate to assess
the efficacy of the particles.
[0077] The transpore tape was stretched on a sample holder and
concentration of 2 mg/cm.sup.2 of the sample was dispensed
uniformly using a syringe. Parafilm (ex. Pechiney Plastic
Packaging, USA) was used as a finger coat and the sample was spread
uniformly on the transpore tape. The film was allowed to dry for
fifteen minutes before performing the measurement. The sample was
exposed to a UV lamp and the transmittance spectrum in the UV
region was collected using SPF-2905 spectrophotometer (ex
Optometrics Corporation, USA). The instrument scans six spots for a
given sample. The experiment was repeated three times and the data
reported is thus an average of 18 data points. The reference
transmittance scan was obtained using a blank plate, with no sample
on transpore tape.
[0078] For visible region, transpore tape was pasted on to a quartz
plate and the same concentration (2 mg/cm.sup.2) of sample was
applied and spread uniformly. The sample was allowed to dry for
fifteen minutes followed by exposure to Sunlamp (Atlas Suntest M/C
CPS+) and the transmittance spectrum was collected using a
radiometer detector (ex. International Light Technologies).
[0079] The transmission spectra of example 2 and example 3 in the
visible region are shown in FIG. 2(a) and in the UV region in FIG.
2(b). The data in FIGS. 2(a) and 2(b) indicates that hollow titania
microspheres prepared as per the invention transmits less light as
compared to a control composition in the visible region and is
comparable in the UV region. Further, the compositions of examples
2 and 3 when applied on the skin provided almost the same skin
appearance. Thus, the hollow particle of the invention provides for
better visible light protection as compared to a known composition
with no compromise on the UV protection and skin appearance.
Example 4 and 5
Experiments to Demonstrate the Usefulness of Using Coated
Micropheres in the Invention
[0080] Samples of hollow titania microspheres as per process of
example 1 were prepared with coating (example 4) and without
coating (example 5). It is desirable that the microspheres for use
in the personal care composition of the invention have high
photoprotection efficacy but low photocatalytic efficacy. The
photocatalytic efficacy was measured using methylene blue (a dye
used as a surrogate for organic sunscreens used in personal care
compositions). Samples of particles of example 4 and 5 were
suspended in water by sonication for 30 minutes. After sonication,
methylene blue was added and then the samples exposed to sunlight
using a solar simulator (Suntest CPS +) at 500 mW for 20 minutes.
After exposure, the samples were centrifuged to remove the
particles and the supernatant used for absorbance measurement.
Absorbance of the supernatant was measured using a Nanodrop
(ThermoScientific) spectrophotometer.
[0081] The data is presented in FIG. 3. The data indicates that use
of microspheres as per the invention provides for enhanced
stability of photosensitive compounds (e.g. organic sunscreens)
used in personal care compositions.
* * * * *